1. Field of the Invention
This invention relates to external fixation devices for holding bone fragments in place, and, more particularly, to such devices for holding such fragments at a proximal end of the ulna.
2. Summary of the Background Art
The patent literature includes a number of patents describing assemblies including medullar pins or screws to be installed to extend longitudinally within the ulna from its proximal end at the elbow, providing for the positive fixation of fractures of the ulna at or near the elbow joint. For example, U.S. Pat. Nos. 3,763,855 and 4,212,294 describe versions an elongated assembly including a first element that is inserted from the side through the cortex of the bone into the soft central channel of the bone below the fracture and a second element in the form of a flexible medullar pin extending through the transverse hole in the first element, with external threads of the medullar pin engaging threads within the transverse hole. In another such example, U.S. Pat. No. 5,549,609 describes a bone fixation assembly for fracture(s) of the upper ulna, the ulna having an olecranon and a proximate end, comprising a elongated medullary pin and a head member. The elongated medullar pin has a longitudinal axis and distal and proximal ends and at least one aperture at its distal end for transverse locking screw(s). The head member is disposed at the proximal end of the pin for transmitting force to the olecranon along the longitudinal axis of the pin as the head member is tightened. The head member comprising at least one inwardly extending, projecting, pointed portion.
U.S. Pat. No. 5,057,110 describes an intramedullar nail for the treatment of fractures of long tubular bones, made of a shaft having a nail tip and at least one fixation screw. A portion of the nail tip is made of absorbable material. The fixation screws penetrate the bone and a section of the nail, causing the bone and nail to be attached.
U.S. Pat. Nos. 5,102,411 and 6,152,925 describe versions of an external fixation device for use at the elbow, with a hinge mechanism aligned with the elbow, an upper assembly extending along the upper arm from the hinge assembly to be fastened into the bone therein by one or more bone pins, and a lower assembly extending along the lower arm from the hinge assembly to be fastened into a bone therein by one or more bone pins.
Other patents describe external fixation devices installed to extend along a broken bone with pins from the device extending into the side of the bone, at least on both sides of the fracture. For example, U.S. Pat. No. 3,877,424 describes a method comprising inserting at least one pin in each major fragment of bone with a portion of the pins extending above the skin surface, drawing the pins toward one another and applying a bridge to the pins to hold them in place under compression parallel to the bone being repaired, together with an apparatus including at least two elongated pins adapted to be inserted at one end into the bone on opposite sides of a fracture, bridge means engaging the other ends and compression means acting on the pins generally parallel to the bone. U.S. Pat. Nos. 5,545,162, 6,197,027, and 6,585,736 describe external fixation devices particularly configured for use with a fractured distal radius.